I just want to let you know that I had a leak from my exhaust side tappet cover at only 6000 kms. I changed the seal and everything is back to normal.
Keep an eye on yours, mine was leaking really badly.
A very very wise man once said “it’s more fun to ride a slow bike fast, than a fast bike slow”.
"Now then get your weapons... and go out to the open country to hunt some wild game for me"
“I've noticed that everyone who is for abortion has already been born.”
Ditto...for some time now.
Replacing the O-ring solved the problem.
I replaced the valve cover o-rings 4,000 miles ago. The other day I adjusted the valves and noticed the o-rings were starting to go flat. Normally I would have changed them but I am really curious how long they will last. These are non-Yamaha bought at a local place that specializes in different kinds of seals and gaskets and o-rings.
Did you guys use genuine Yamaha o-ring?
Long live the internal combustion engine!
I use ordinary 1 1/4" O-rings with roughly the same size cross-section. They cost me 40 cents each at the local machine shop. The original (exhaust side) lasted about 30,000 km before it needed replacing...and I check my valves often!
I have more problems with the valve cover screws! Stripped one on the exhaust side a while back and had to replace it with a stud...now, I have another one on the exhaust side that feels "stripped" as well!
The Yamaha o-rings fail quickly when engine temps are high, especially on the exhaust side. I use Viton o-rings and replace them every other change. Cheaper to buy in bulk from an industrial power supply than from Yamaha.